Which of the following is not a ECG finding in hyperkalemia? (AIIMS May 2010)
|A||Tall T wave|
|B||Prolong PR interval|
|C||Tall P wave|
Tall P wave
Causes of Hyperkalemia (Ref. Hari ed. 18th Table 45.5, Pg 356)
1. Renal failure
2. Decreased distal flow (i.e., decreased effective circulating arterial volume)
3. Decreased K+ secretion
Impaired Na+ reabsorption
1. Primary hypoaldosteronism: adrenal insufficiency, adrenal enzyme deficiency (21-hydroxylase, 3-hydroxysteroid dehydrogenase, corticosterone methyl oxidase)
2. Secondary hypoaldosteronism: hyporeninemia, drugs (ACE inhibitors, NSAIDs, heparin) RTA IV
3. Resistance to aldosterone: pseudohypoaldosteronism, tubulointerstitial disease, drugs (K+-sparing diuretics, trimethoprim, pentamidine)
Enhanced Cl- reabsorption (chloride shunt)
1. Gordon's syndrome
1. Malaise, muscle weakness, which may progress to flaccid paralysis and hypoventilation if the respiratory muscles are involved.
2. Cardiac toxicity: Arrhythmia, palpitation, sudden death
a. The earliest electrocardiographic changes include peaked T waves.
b. More severe degrees of hyperkalemia result in a prolonged PR interval and QRS duration.
c. Atrioventricular conduction delay.
d. Loss of P waves.
e. Progressive widening of the QRS complex sine wave pattern.
f. The terminal event is usually ventricular fibrillation or asystole.
Signs and symptoms
3. Sudden Death.
Treatment of Acute hyperkalemia
1. Severe hyperkalemia requires emergent treatment directed at minimizing membrane depolarization, shifting K+ into cells, and promoting K+ loss.
2. Administration of calcium gluconate decreases membrane excitability. But it does not reduce S. potassium level.
3. Insulin with glucose causes K+ to shift into cells. It is the fastest, earliest & the best way to reduce S. potassium level.
4. When administered parenterally or in nebulized form, 2-adrenergic agonists promote cellular uptake of K+
5. There is no role of NaHCO3 in the treatment of hyperkalemia (Ref: Harrison, 18th edition page 359).
Treatment of Chronic hyperkalemia
Removal of K+ can be achieved using diuretics, cation-exchange resin, or dialysis.